gamma rays from the neutral pion and their energies can be est imated f rom the shower wid th observed in the chambers.

A complex exper iment to study scatter­ing ampl i tudes of neutral kaons on pro­tons (in the momentum range 15 to 25 GeV/c), being carr ied out by a team from Dubna, started taking data in May of this year. The detect ion equipment inc ludes a spectrometer wi th magneto­str ict ive spark chambers p laced before and after the magnet, all operat ing on- l ine to a BESM-3 computer. The system is t r iggered by hodoscope counters. 100 000 t r iggers had been registered pr ior to the shutdown at a rate of twenty per cyc le and prel iminary results on the regene­ration cross-sect ion may be presented at the Kiev Conference.

An exper iment on elast ic scat ter ing of negative part ic les on hydrogen using a hodoscope system of sc int i l la t ion counters has begun tak ing data and has some pre­l iminary results.

The study of elastic proton-proton and proton-deuteron scat ter ing, using the internal beam of the synchrot ron, has been comple ted. This exper iment used the gas jet target developed at Dubna (see vol . 10 page 190) together wi th semi ­conductor detectors and had very low background.

A search for new heavy part ic les and ant inucle i wi th l i fet imes in excess of 1 0 _ 8 s is in progress using t ime-of- f l ight t ech ­niques.

Observat ion of ant ihe l ium—3 in an ex­per iment wh ich f in ished at the end of last year has already been reported. Five such nuclei were detected, for the f irst time., f rom among 2 X 1 0 1 1 part ic les, using Che-renkov and scint i l lat ion counters.

More recently, exper iments wi th ant i -protons and ant ideuterons were comple ted measur ing such things as the mass, absorpt ion cross-sect ions and b ind ing energies for the ant ideuteron. The total cross-sect ions of ant iproton-deuteron and ant ideuteron-proton have been compared as a check of CPT invar iance. No di f fer­ence between the cross-sect ions was detected wi th in the l imits of the exper i ­mental errors.

The missing mass spectrometer exper i ­ment (the second CERN-Serpukhov exper i ­ment wh ich was descr ibed in vo l . 10 page 78), has begun wel l . On 18 May all the equipment was assembled and the first data tak ing run began on 28 June using a pion beam set at 25 GeV/c to scour the missing mass range f rom 2 to 3.5 GeV. The qual i ty of the beam has been very good and it is hoped to have re­corded several mi l l ion t r iggers before the end of the year. There have been d i f f i ­cul t ies at the Geneva end of the 'aero­plane-on- l ine' system, whereby it had been hoped to have very rapid turn-round of the data tapes from the exper iment brought dai ly to CERN for analysis on the CDC 6600, but the use of a telex pr int-out f rom CERN to the local control room in the Serpukhov exper imental hall has given a 24 hour feed back of results. A l ink be­tween the CDC 3100, wh ich is used on­line in the exper iment, to the BEMC 6 large computer at Serpukhov is being developed so that the Serpukhov -scien­tists in the co l laborat ion can part ic ipate more ful ly in the analysis stage. The co l ­laborat ion is going extremely wel l .

Among the exper iments wh ich are in course of preparat ion are a search for the W boson, a search for Dirac monopoles, a study of polar izat ion effects in high energy negative pion-proton scatter ing (a Saclay/Serpukhov experiment) and a study of p ion-electron scatter ing which wi l l be carr ied out by scient ists f rom Dubna, Ser­pukhov and several Laborator ies in the USA. (This is the f irst Soviet-American col laborat ion in an exper iment involving equipment transfer. The USA component of the jo int team wi l l be led by D .J . Dr ickey of the University of Cal i fornia Los Angeles. Also, two Soviet scient ists, P. Ermolov and A. Mukhin, are at Batavia and Soviet teams wi l l be able to propose exper iments for the USA 500 GeV acceler­ator.) The exper imental programme of neutr ino research is sti l l being evolved. It wi l l use the heavy l iquid bubble chamber, SKAT, wh ich is scheduled to be in oper­ation by the end of 1972. The other main component of the bubble chamber pro­gramme wi l l involve Mirabel le and has been descr ibed before in CERN COURIER (vol. 10, page 118).

BATAVIA 66 MeV linac beam On 30 July the f irst three l inac tanks were all in operat ion to produce a proton beam accelerated to 66 MeV. Of the remaining six tanks — tanks 4 and 5 are comple ted ; tanks 6, 7 and 8 are being assembled; the last components for tank 9 are ex­pected to be del ivered soon. The l inac's next big date is 1 October when it wi l l del iver a 139 MeV beam to the 8 GeV Booster.

A quarter of the Booster ring is instal led and has been powered. Part of the in­ject ion l ine, wh ich wi l l br ing in a 200 MeV beam when the l inac is completed and is in operat ion, cont ro l led and adjusted via a computer . The f irst two r.f. cavit ies for the Booster were moved into place on the scheduled date of 24 July. (These scheduled dates, known to some by the resounding name of 'mi le stones', are referred to by those responsible for meet­ing them as 'mi l l stones' . But they haven't missed many yet.)

The f irst f ive cel ls of the main magnet ring were instal led by the end of July. A hundred magnets had been completed by then and manufacture, by the Laboratory itself, of the inner coi ls wh ich need more careful contro l is ahead of schedule and ahead of the rate at wh ich outside manu­facturers are produc ing the outer coi ls.

OXFORD Fast PEPR System In the course of measur ing its f irst 13 000 product ion events, a PEPR device con­structed at Oxford University in 1966-67, has measured f i lm of 740 MeV/c negative p ion-proton interact ions at rates of be­tween 150 and 430 events per hour. The upper rate is obta ined when measuring two prong events (on average one event per 4 frames) for wh ich frame number, topology and vertex guidance (to 1 mm accuracy on f i lm in one view) have been def ined by an operator at a convent ional scanning table. Whi le the exper iment was chosen to be a s imple one to measure and the total number of events in it was smal l , the Oxford group believes its results are a foretaste of the high measur-

258

Table : — Vital stat ist ics for the measurement of a 10 000 event batch of two prong events on f i lm of 740 MeV/c negative p ion-proton inter­act ions.

Vertex posit ion in one v iew zoned to : Elapsed t ime: PDP6 t ime: Auto events: Helped events: Total events: Total events/PDP 6 t ime:

Helped events/total events: MATCHING/ GEOMETRY fa i lures: Kinemat ics fa i lures:

Helix f it s tat ist ics: Peak:

1 % tai l beyond:

4 mm 80 hours 64.6 hours 8728 1370 10 098

156 events/h

1 3 . 5 %

1 3 %

1 .5%

7 |im 25 \im

ing speeds that CRT devices wi l l be reaching routinely in the next year or so.

PEPR is a CRT line d ig i t iser of the type f irst proposed and const ructed by L. Pless at MIT. The Oxford system is s imi lar to that of MIT except that a PDP6 com­puter is used rather than a PDP10, and an improved CRT has been developed to give a smal ler and br ighter l ine on the f i lm. The programs used at Oxford occupy 30 K words of storage wi th the general strategy der ived f rom the successful POLLY system at Argonne (CERN COURIER vol . 9, page 275) wh ich enables t racks associated wi th a vertex to be rapidly d is t inguished f rom all others in the zone of interest. The main di f ference f rom POLLY is that all detect ion, fo l low­ing, and measurement of t racks is done by using a 1 mm long line image on the f i lm (formed by the act ion of quadrupoles on the electron beam of the CRT).

The line is handled by basic scanning routines, which are the only part of the program not wr i t ten in Fortran IV. A par­t icu lar ly fast t rack- fo l lowing program has been wr i t ten, wh ich maintains the l ine tangent ia l to the t rack whi le predict ing along its length. A typ ica l beam track f rom the 80 cm hydrogen bubble chamber can be fo l lowed and complete ly measured in about 60 ms. The program outputs 'master points' on all t racks wh ich it has associated with a vertex in a given view. A special ly wr i t ten off- l ine MATCH pro­gram matches the t rack images f rom all three views, labels them, and d iscards any redundant t racks wh ich may have appeared to intersect the vertex in some view. The remaining t racks are ready for input to the geometr ica l reconstruct ion program where they are indist inguishable

The PEPR system for the automatic measurement of bubble chamber film constructed at Oxford University. It is currently measuring film at rates in excess of 150 events per hour and could be capable of development to very high measuring speeds.

(Photo Oxford University)

f rom manual measurements — except that, as wi th HPD and other automat ic machines, the helix fit residuals are found to 'peak' some 3 j im lower.

The PEPR programs inc lude 'HELP' faci l i t ies using a monitor CRT on wh ich the program presents to the operator a local scan of any area of f i lm in wh ich some doubt or ambigui ty has ar isen. The operator can then indicate exact vertex posi t ion, clear points on t racks, etc. using a l ight pen. However, a l lowing the oper­ator to intervene and attempt to rescue all doubt fu l events on-l ine, reduces the measur ing rate to only 150 events/hour.

In future product ion runs, a compromise may be adopted in wh ich events whose beam t rack is not clear ly d is t inguishable f rom other beam tracks in at least two views (by 100 j im for at least 5 mm) are detected in the pre-scan and not pre­sented to PEPR at al l . This wi l l reduce the need for operator intervent ion to around 5 % of events measured, so that a measur ing rate of 200-300 events per hour is mainta ined.

The next product ion run wi l l be some

100 000 events on f i lm from the CERN 2 m hydrogen bubble chamber of 3.6 GeV/c negative kaon-proton interact ions. Exper i ­ence ' tuning up' for this run indicates that four and six prongs are measured as fast as two prongs. New programs have been inc luded to measure ionization of all t racks and end points of s topping t racks. Both use the spot (instead of the usual l ine), scanning it across the t rack at 10 | im or #2Q j im intervals. Prel iminary measurements on minimum ionizing t racks show a standard deviat ion of about 1 0 % on the measured ionizat ion: this measure­ment takes about 100 ms extra per t rack output.

Once the negative kaon-proton exper i ­ment is sol id ly in product ion, development work wi l l begin on dispensing wi th the prescan informat ion al together for exper i ­ments in wh ich the f i lm qual i ty is good (i.e. uni form i l luminat ion and beam d is t r i ­but ion). At the same t ime, a three-view PEPR is being constructed to al low imme­diate access to other v iews of a given track, to avoid the disadvantages of do ing a 'post mor tem' match as at present.

259

a good start for something bigger you can build up

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Ultra High Vacuum Meter IMG - U 2

Measuring range: 10-3 to 10-1 3 Torr Indication: linear and logarithmic

4 5

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T O R R UHV IONIZATION GAUGE CONTROL UNIT IMG-U2

This instrument is compact , rel iable and extremely accurate. It is the ideal instrument for exact ing requirements, in laboratory and product ion appl icat ions where the success of any vacuum pro­cess depends on accurate and repro­ducib le indicat ion of the pressure in the high and ultra high vacuum range. For example, in nuclear research, in space simulat ion chambers, in the in­vest igat ion of absolutely c lean sur­faces, and in UHV coat ing plants etc. In developing the IMG-U 2, which has evolved f rom the wel l -known IMG-U 1 — the aim was to const ruct , a hot cathode ionisat ion manometer so rel i ­able in operat ion that the major ad ­vantages of this pr inc ip le, namely, ac­curate and reproducib le indicat ion of pressure, could be ult i l ised to the fu l ­lest possible extent. Not only does the IMG-U 2 ful f i l this basic aim, but a lso: — its measuring range is extended in

the ultra high vacuum range; — it has an addi t ional logar i thmic mea­

suring range; — it can be operated wi th any Bayard-

Alpert gauge head.

Other features: — very wide measur ing range, total

pressure indicat ion over 11 l inear decades;

— cont inuous pressure indicat ion f rom 5 x 1 0 - 4 to 5 x 1 0 - 1 1 on logar i thmic scale, respectively 5 x 10-s to 5 x 10-12 ;

— extended emission range, wi th stabi ­l ised, inf initely var iable emission cur­

rent; — high stabil i ty of the measurement

ampl i f ier with minimum zero point dr i f t ;

— gauge factors adjustable, f ixed at C = 5, 10 and 25, infinitely variable f rom 5 - 3 0 ;

— selector switch provided for operat­ing gauges with a modulator ;

— f i lament protect ion relay which swit­ches off the f i lament in the event of excessive.pressure rise (provided wi th an addit ional make and break con ­tact for other monitor ing or contro l funct ions) ;

— signal outputs of 10 and 100 mV al low connect ion of addi t ional instru­ments for moni tor ing, contro l and re­gu la t ing ;

- t h e IMG-U 2 can be used as a 19" rack module, or if provided with side panels, as a bench model which can be stacked.

Gauge Heads for use wi th the IMG-U 2 Any Bayard-Alpert ionisation manometer gauge heads (either wi th or wi thout modulator) can be operated wi th this instrument, but to obtain the guaran­teed performance of the IMG-U 2, it is advisable to use gauge heads either built or recommended by BALZERS: — glass gauge heads with 2 pure metal

(W), or burnout proof oxide cathodes with hard glass seal suitable for con ­nect ing to pyrex glass;

— highly sensit ive immersion gauge heads on metal f langes, wi th inter­changeable tungsten cathodes and

either wi th or wi thout a modulator, depending on the gauge head type.

We also manufacture: Thermocouple- , Pirani-, Co ld- and Hot-cathode-Vacuum meters, Quadrupole mass spectrometers, vacuum switches for the medium and high vacuum range, Halogen leak detectors and the Halo-gen-sniff ler.

Please request further detai ls.

BALZERS AKTIENGESELLSCHAFT fur Hochvakuumtechnik und Dunne Schichten FL-9496 Balzers • Principal i ty of Liechtenstein

United K ingdom: BALZERS HIGH VACUUM LIMITED Berkhamsted, Herts., Te lephone: Berkhamsted 2181

261

CERN Stores

The Surplus Stock and Salvage sect ion has a large select ion of used e lect ronic materials, also used electronic components in good condi t ion.

Those interested should contact the Head of Stores for further informat ion at the fo l lowing address:

CERN - 1211 Geneva 23.

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Ask for free literature by sending this coupon • hose catalogue • hydraul ic hose catalogue • air hose cata logue • o-r ings and seals catalogue • rubber sheet ing sample book • rubber and plast ics prof i les • protect ive rubber gloves • MAAGinform per iodical • d ie lectr ic materials

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N E W ! from EH-Research Laboratories pulse generator Model G-710

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Dimensions: Cabinet 3 " - W high 8" in w ide

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For further information please contact:

Omni Roil Omni Ray AG, Instrument Department Dufourstrasse 56 - 8008 ZURICH Tel (051) 478200 - Telex 53239

262

CHASSIS ALIMENTATION CAMAC • Ce châssis pour t i ro irs 5 unités est destiné à

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o Util ise l 'al imentation type P 7 A L J 1 0 délivrant: + & — 24 V 3 A + & — 12 V 3 A

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Tension de sort ie I ± 24 V I ± 12 V + 6 V I — 6 V I + 2 0 0 V

Plage de réglage ± 2 % ± 2 % + 5 à —15 % + 5 à —15 % ± 10 %

Précis ion du réglage ± 5.10" 4 ± 5.10~4 ± 1CT3 ± 10~3

Taux de régulat ion en fonct ion du réseau , R i n _ 4

( + 1 0 % à — 1 2 % ) - D - n u

Régulat ion pour 100 % de var iat ion de charge et des * + 1 Q _ 3

var iat ions du réseau ( + 1 0 % à —12 %) ~~

Stabi l i té g lobale (réseau-charge-température) ± 5 .10 - 3 I ± 10~2 I +2 ,5 .10" 2 ± 1 0 - 2 ± 10~2

Coeff ic ient de température de + 1 0 °C à + 4 5 °C 5.10- 5/°C | 2.10~ 4/ oC | 3.10- 4/°C

Dérive en fonct ion du temps 8 h 10~3

24 h. ± 3.10- 3

6 mois ± 5.10" 3

Fluctuat ions en sort ie crête à crête < 2 mV < 2 mV < 5 mV < 5 mV 5 mV

Réponse transi toire (overshoot et undershoot < 10 % ) < 20 jis

Stabi l isat ion thermique ^ 30 mn

Plage de température 0 °C à + 5 5 °C

Impédance dynamique de sort ie jusqu 'à 100 kHz < 0,3 Q

Sécur i té é lectronique en courant indiv iduel le par l imi tat ion de courant fusible

Dis jonct ion de l 'a l imentat ion provoquée par + 1 5 ° / + 1 5 ° / + 2 5 ° / + 1 5 % des surtensions de : 0 0 0

Protect ion thermique 2 v ig i thermes: 0 max. —20 °C: voyant blanc 0 max.: coupure de l 'a l imentat ion

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265

CHRONETIC.

Gate problems stop here

The GA100/N First gate amplif ier

module w i t h bu i l t - in power supply to conserve

premium bin power.

Inputs: Lo In :

Direct-coupled "b r i dg ­i n g " input for N I M -

standard fast logic or complement logic signals.

H i - l n : Direct-coupled for

NIM-standard slow data transmission signals. Also

accepts negative signals ( - 4 to - 1 2 V ) .

Outputs: Fanout:

Two independent outputs per section.

Levels: Normal or complement.

" 1 " = 10V at 250 mA max.

" 0 " = sinks up to 200 mA at output

voltage < 1 V.

W i d t h : Approximately

same as input w id th .

Risetime: 100 nsec (can be changed to a m in imum of 50 nsec).

MODEL GA100/N

GATE AMPLIFIER

HI OUTPUT

MODEL GD150/N

DELAY GATE

N LO

5 ©

KM Hl 2 \

OVERLOAD

N I L 0

HI OUTPUT

1

H I 2

DELAY OUT

| ^ 1

f t 1

DELAYED OUTPUTS

LO IT "sir LO

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* USA .MADE IN « USA

^

The GD150/N Precision delay and gate functions provided in one module .

Inputs: Lo In : NIM-standard fast logic signal of w id th w ider than 2 nsec. Hi I n : NIM-standard slow data transmission signals ( + 3 t o + 1 2 V ) . Also accepts negative signals ié-2 to - 1 2 V ) .

One Shot: One and only one output per switch activation.

Blank I n : NIM-standard fast logic signals of w id th greater than 5 nsec. Delayed out­puts are blanked for dura­t ion of blanking input.

Timers (delay and w id th ) : Range: 0.1 /usee to 110 /xsec. Accuracy: 10 nsec or ± 5 % of setting. Random j i t ter : < 1 part in 10*.

Outputs: Delay: One normal and one complement N I M -standard fast logic output for durat ion of delay interval.

Hi Ou t : + 2 . 5 to + 1 0 V , adjustable; for durat ion of w id th interval.

Lo O u t : One " d u a l " normal and one " d u a l " complement ; for durat ion of w id th interval.

NUCLEAR INSTRUMENTATION DIVISION

Make the most of the gating features of each — o r combine them for greater fanout and more flexibil i ty. For addit ional information on the solution of your gate problems, contact EG&G Inc., Nuclear Instrumentation Division, 36 Congress Street, Salem, Massachusetts 01970. Phone (617) 745-3200. Cable: EGGINC-Salem. TWX: 710-347-6741. Telex: 949469.

267

Tips + Topics

P.O. Box, 8021 Zurich, Tel. (051) 42 99 00 baerlocher